Vasomoter responses are conducted along arterioles and feed arteries through cell-to-cell coupling as enabled by gap junctions. The properties of the conduction differ between vascular beds that supply tissues that differ in structure, function, and sympathetic innervation. The Specific Aim of this study is to examine conducted vasomoter responses as related to connexin isoform expression in endothelial and smooth muscle cells of resistance microvessels (arterioles and feed arteries) that are innervated by sympathetic nerves (hamster retractor muscle) relative to microvessels that are not (hamster cheek pouch epithelium). Complementary experiments will determine how these parameters are effected by acute alterations in sympathetic neurotransmission. The long- term goal is to understand how the sympathetic nervous system influences the molecular determinants of conduction in microvessels that control oxygen transport to tissues. Understanding of such regulation of connexin expression and function will aid in the treatment of diseases involving gap junction dysfunction.